Method of making vented rubber members



May 29, 1962 H. E. BOWERMAN METHOD OF MAKING VENTED RUBBER MEMBERS.Filed March 1.7, 1960 INVENTOR. HULIE E. BOWERMAN ATTORNEYS UnitedStates Patent 3,036,339 METHOD OF MAKING VENTED RUBBER MEMBERS Hulie E.Bower-man, 904 Meadow Oaks, Arlington, Tex. Filed Mar. 17, 1960, Ser.No. 15,706 1 Claim. (Cl. 18-475) This invention relates to improvementsin the manufacture of rubber members for use under high pressures in oilwells, and especially to a method of improving sucker rod guidescommonly used during the pumping of fluids such as oil and associatedliquids from wells. In this type of service a sucker rod string isreciprocated by conventional means within a string of tubing near thelower end of which there is positioned a conventional working barrelwith its standing valve, a traveling plunger and its valve and sealingelements being attached to the lower end of the rod string.

This is a continuation in part of my copendiug application entitledSucker Rod Guides, Serial Number 735,- 312, filed May 14, 1958, nowPatent No. 3,001,834.

Guides of the general type to which my novel improvements are directedare illustrated by Patent 2,604,364 to Ward showing a body ofrubber-like material serving as a bearing whereby the sucker rod, itscouplings and the like, are maintained centered within the tubing toprevent wearing of the metal parts as the rod moves up and down duringstroking of the pump. An embedded metal clip serves to increase the gripon the rod by the rubber guide which is attached thereto by passing therod radially through a slot or opening in the guide and spring clip. Therubber or rubber-like covering of the clip also serves to protect itfrom deterioration such as by electrolytic or chemical actions.

In the course of manufacturing these conventional guides, the clip isembedded in a suitable quantity of the rubber-like material in a moldand bonded therein during curing of the rubber as by vulcanization.However, in this process there are entrapped minute pockets of gases orother material resulting in voids in the rubber. There may also occurweak spots in the knitting together of the particles of the rubber massor even undesirable laminations in the rubber structure.

When these guides are subsequently lowered on a sucker rod string into awell during pumping of the fluid therein, the guides are commonlyimmersed under hydrostatic pressures of several hundred pounds persquare inch and in deeper wells these pressures may even exceed 2,000 to3,000 pounds per square inch. Such submergence may continue for days,weeks or even months, during which time gas particles or liquids whichgassify under lower pressures penetrate the body of the guide throughits pores and occupy the voids therein.

Should the standing valve fall at the bottom of the tubing string andpermit a lowering of the fluid column in the tubing about the guidethese entrapped gases, or expansible liquids which turn to gases atlowered pressures, may expand the body of the guide to such a degree asto cause it to bind tightly in the tubing; then, when stroking of thepump is again attempted, the rod string binds and is caused to buckle orpull in two.

Also, when the rod string is pulled for servicing the pump, and theattached guides are retrieved from the well tubing and removed from thestatic pressure head of the fluid column, the entrapped gases orgassifying liquids may expand the guides inside the tubing and causebinding of the sucker rod, or may require a stripping job. Even if thisshould not occur while the rods and guides are being withdrawn from thetubing, these expansive forces continue to work while the guides are outof the well and frequently so expand them that they will not re-3,035,339 Patented May 29, 1962 I method of improving cured rubber-likemembers wherein, after the members are molded and cured, they arepierced or otherwise cut by a sharp instrument to provide punctures ofsmall cross-section which are relatively closely spaced, which extenddeeply into the rubber-like members and which vent internal voids andpockets that otherwise tend to trap expansible fluids when the membersare immersed at high pressures in well fluids. The improved method oftreating a molded and cured rubber member produces the inobvious resultthat the useful life of the perforated rubber members is actuallygreatly increased even though it would appear upon casual considerationthat piercing the members might tend to decrease their life expectancy.

My novel improvement in the method of making such members results inmuch longer life and in the elimination of many of the defects inconventional guides, and will be readily appreciated by those skilled inthe art from the following description together with the accompanyingdrawings in which:

FIGURE 1 is an elevation view of a punctured guide mounted on a suckerrod, the punctures being exaggerated in width to make them clearlyvisible in the drawing.

FIGURE 2 is a section along line 2-2 of FIGURE 1.

In the several views like references indicate similar elements wherein:5 is a sucker rod; 6 is a rubber-like guide body; 7 is a metal clip; 7aindicates the opening in .the clip registering with the opening 6a inthe body for passing the rod into the bore 6b of the guide; 8-8 arevoids in the rubber body, exaggerated for easy identification, 9-9 arepunctures, exaggerated in width, extending into the voids from theperiphery of the guide body.

My invention is directed to the provision of a method of manufacturingrubber parts, such as the illustrated sucker rod guide, said methodincluding perforation of the body whereby the entrapped gases andgassifying liquids are permitted to escape from the body throughpunctures made in the body by a suitable sharp instrument driveninwardly into the rubber to a suitably predetermined depth, and at suchintervals of spacing as are required to effectively perforate theobjectionable voids in the rubber. In general, it appears thatsufficient punctures are provided, Where such punctures are relativelydeep, if the punctures are spaced apart by distances not exceeding thedepths of the punctures. It is important that these providing escapepassages not be of such depth as to expose the clip directly to thecorrosive eiiects of the gases and liquids entrapped within the body ofthe guide.

It is also important that these punctures be pierced or otherwise cut inthe rubber body after it is fully cured. The piercing is particularlyeffective after the body is cured since attempts to form such smallopenings during molding are frustrated by the tendency of the latter toseal over. Moreover, openings or depressions which are formed duringmolding and prior to completion of the curing step result in smoothbores having continuous sealed walls which are no more capable ofventing the internal voids than are the other walls of the moldedproduct. The piercings or fissures or punctures should extend deeplyinto the cured body in order to vent as many voids as possible, butshould terminate short of metal parts embedded therein. Although thepunctures are radially disposed as shown in the drawing there is noreason why other angles would not be satisfactory for the purpose ofventing internal voids. In most cases, it is desirable that thepunctures be made by a thin sharp piercing instrument without removal ofrubber material so that the punctures tend to close when the instrumentis withdrawn, thereby discouraging entrance into the punctured hole offoreign matter. I V I desire to point out that other types of wellrubbers, such as guides comprising all-rubber sleeves which arestretched over the ends of rods or tubings and which may depend on theinherent resilient memory of the rubber to provide the necessary grip ona sucker rod or tubing or drill pipe, may be protected by my novelmethod from these injurious effects of gases and gassifying liquidsentrapped under high pressures in their bodies. All such are intended tobe embraced by the following claim,

I claim:

The method of making a rubber member for use at high pressures in oilwells including the following steps: molding the rubber member, curingthe rubber, and sub- References Cited in the file of this patent UNITEDSTATES PATENTS 1,364,132, Miller Jan. 4, 1921 1,388,453 Davidson Aug.23, 1921 1,983,464 Kitchen Dec. 4, 1934 2,604,364 Ward July 22, 19522,770,282 Herzegh Nov. 13, 1956

